Power-transmission device.



in. 851,842. PATENTED APR; 30,1907.

- T. SEARS.

. POWER TRANSMISSION DEVICE.- AAAAAAAAAAA 1'1' nnnn 013.6, 1906.

- QM MMUWW WitnessBsIX Invent 5&4 (SU;SL. YYLA; 7 (n1 Attorney 3S engaging the pair of splined gears and adapt- UNITE' sra'rns PATENT onrron.

' WILLARD THOMAS SEARS, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T NILES-BEMENT-POND COMPANY, OF JERSEY CITY, NEW'JERSEY.

POWER-TRANSMISSION DEVICE.

Specification of Letters Patent.

I Application filed betcha: 6,1906. Serial No. 337,693.

Patented April 30, 1907.

To all whom it 7nayc0ncern:

' Be it known that I, WVILILARD THOMAS SEARS, a'citizen of-the United States, residing volved relatively shifting toothed members for changingthe rate of motion or the direction of motion or the condition from rest to motion and viceversa, and relates to improved means forguarding against, first, the difficulties'of intermeshing the teeth when teeth do not happen to'match tooth-spaces;

second, the liability of the transmission of heavy work through teeth" but partially engaged; and third,-the labor of shifting teeth I into engagement while they are under the strain of heavy duty.

I from the following description taken in con- 5 The inventionwill be readily understood nection with the accompanying drawing in .which Figured is a front elevation of an apparatus embodying anexemplification of my invention, and Fig. 2 a panorama of the cam.

-'Inthe drawing:.1, indicates housing- .parts: 2,. the driving shaft: 3, the driven shaft: A, a gear fast on the driven shaft: 5, a

second but larger gear fast on the-driven shaft 6, a pair of gears fast with each other and splined on the driving shaft: 7, a shifter ed to'slid'e them so that its'component gears {may mesh with either of the mating gears,

respectively, on the driving shaft: 8, a fric- .40

tion clutch, w hich may be of any desired or suitable ordinary construction; 9, an" endwise movable .bar to 'serve in engaging and disengaging the clutch: 10, a cylindrical cam having a plurality of cam grooves,' one groove being engaged by a pin projecting from shifter 7 andthe other being engaged by a pin projecting from the clutch-operating bar: 11, the cam-groove controlling the clutch-operating bar: 12, the cam groove controlling the shifter: and 13, a handle for turning the cam.

Ignore, for the present, the cam, and assume the presence of any appropriate handle means for operating the shifter and the clutch bar independently, and assume that the friction clutch is disengaged and that the gears 6 are in neutral or idle position and at rest. If, now, an attempt be made to slide the gear into engagement with one of the mating ears that attempt would be very apt to be de eatcd by the failure of tooth-ends to register with tooth-s aces, under which circumstances it would e impossible to engage the gears until after an angular adjustment of one of the gears had been effected. Assume, now, that the clutch is engaged and the drivin shaft and sliding gears are in motion and that the sliding gears arein neutral idleposition. 1f, under these conditions, an attempt be made to engage the gears an opportunity will quickly present itself for the entry of teeth into tooth-spaces, but the instant such engagement is initiated then the motion is being transmitted through the teeth at full speedand power, and full working strainis thus brought upon the teeth While they may be engaged for but a fraction of their length. This tends to break teeth and. always mutilates the ends of the teeth and, the teeth being under full workin strain, considerable effort would be required to complete the engagement of the teeth. Similarly when-the gears are to be disengaged, considerable effort would be required .in performing the act and toward the end of the-operation the full strain would be imposed upon a mere trifle of tooth lengths.

The present invention is designed to avoid theevils-referred to. These evils have long been recognized as inhering in power transmission devices employing two toothed members,of.one kind or another, to be engaged or disengaged from each 'other,'and

the presentinvent'ion is believed to be available in connection withianysuch transmissionmechanism, as will be understood from the following considerations.

Inthe exemplification the cam is illustrated as being cylindrical and in Fig. 1 the parts are illustrated with the clutch engaged and the driving gear in neutral idle position. A half turn of the cam in the direction of the arrow will first release the clutch, the shifter remaining stationary, the shifter will then move to the left, throwing the siding gear into engagement with gear .4, while the power isoil', and the clutch will then be reengaged, thus putting on the power to the slid into engagement While the power was off, thus avoiding risk and hard work-infShif-ting To disengage the ge'arthe cam ris turnedbagzh S1 to normal position, the first effect 'beingl to" release the clutch and'ciit off the powerjand I then to slide the gear out of'en agement-and then, if the restoring half turn: e completed,

re-engagefthe clutch. [-The'gear, has thus been slid out of engagement 'Wliil6 notnun'der the strain of Work, thus again avoiding risk and hard work duringithe sliding act. If,

While the cam is in neutral position, it be his 'turnediin the direction against the arrow;

then the effect will be as previously-described except that the sliding gear iut Put the gear 5 i stead of gear 4f :5 w

As thus far described it isinianifest that, L I Power transmission apparatus comprising :a pair or toothed members adapted for ena gagement'and disengagement-to and from- While "ample provision has ibeen made for ave ding the transmission of heavy power through partially engaged Eteeth and for Y I avoiding the hard Work of sliding teeth whilej under the strain of work, it willbe apprehended that no mention has been made of the capacity ofthe device for uarding against the clashing of the endsofthe teeth I 'in'attempti1ig"to initiate-thejengagement of.

the teeth. :But this is fullytaken care ofin the device; The clutch being engaged and the driving shaft being in full motion and the sliding-gears :bein din-neutral idle position,

the first effect of t e turning of the camiis to release the elutchand cut off the power. If the-'drivingishaft and slidingvgear were -noW giventiriietos-come :tojrest there, might. be

troubledue'to the clashing 10f. tooth-ends.

. so closely upon the release-of t V the, momentum maintains the driving'shaft Butthe initiation of tooth-engaging follows eclutch that and slidinggear in rotation, an opportunity thus surely presenting itselfforfthe initial en- I nomentum of the parts.

"gagement of the teeth. "When the teeth are i initially engaged then the resistance ofiei'ed the driven shaft arrests the-rotation of the iding gear, the sliding engagement being completed While the'parts are Without rota,- tion; In practice I find it preferable'to so P F POrtiOn the cam'that the clutch will be disengaged just prior to the ends, of the slid- ,ing teeth reaching the face of the mating gearfthus getting the best benefit from the Manymodifications of the invention Will suggest themselves to the skilled machine constructor. I have simply explained the principle ofmy invention and have set forth present contem the best mode in which I at plate applying that principle.

I claim:

operating pait for' throwing the clutch into:

and out of engagement, and a cam positively engaging the shitter'and the clutch-operating part and arranged to hold the clutch engaged and the tooth members disengaged and by movement to firstrelease the clutch and then to initiate the engagement of the tooth mem-'- here While one ofthe tooth members is under theinfi uence of momentum and then to complete the tooth engagement and then engage the clutch, combined substantially as set forth. i

. WILLARD THOMAS SEARS.

-Witne'sses:

ARGHIBA'LD' M. OIBRIEN, SAMUEL C. KANE. 

